1. Field of the Invention
The present invention relates to a light emitting diode, and in particular relates to a light emitting diode package structure.
2. Description of the Related Art
Because light emitting diodes (LED) have several advantages over conventional lamps, such as a longer lifetime, a smaller size, lower power consumption, and higher response speeds, etc., considerable research attention has been recently focused on development thereof.
Conventionally, one way to generate a white light emitting diode (LED) is to coat a yellow phosphor on a blue LED chip. The blue light emitted by the LED chip is then mixed with the complimentary yellow light from phosphor to generate the white light. An LED comprises a semiconductor layer formed on a substrate, such as a GaN layer formed on a sapphire substrate. When the yellow phosphor is illuminated by the semiconductor layer (the reflective index of the GaN is about 2.5) to produce a yellow light, the yellow light may be reflected by a medium with a lower reflective index. Accordingly, an unwanted phenomenon called a “light trapping effect” is produced. Therefore, the light extraction efficiency of the light emitting diode is limited.
Accordingly, there is a need to develop a light emitting diode package structure to reduce or eliminate the light trapping effect to improve the light extraction efficiency of a light emitting diode package structure.